On Mon, 27 May 2019 09:50:02 -0700 (PDT), wrote:

On Saturday, June 23, 2001 at 7:03:48 PM UTC-4, pp wrote:
What about filling the rails with fine dry sand packing it reasonably tight
and wrapping it around the shape you want. This normally prevents those
ugly creases that always ruin your day.

Paul P

" wrote:

i have several arch windows in the front of my house. i would like to
put some Solar Screens on them but cannot find a source for the aluminum
frams with arched windows that are pre bendt into an arch. i was quoted
a price from one shop, well not really a quote, he told me that he has
to pay $70 for just the arch as he does not have a machine for bending
the frame. the aluminum frames are .020 aluminum and am willing to
ruin a few to try it, does anyone know if i can take a piece of
plywood, say 2 feet by 3 feet with some rollers on it like maybe
one on bottom and two on top for rollers(made out of metal and just push
then frames of aluminum through them a few times and bend it into an
arch with enough passes? or can someone think of another way of doing
it without paying for the $70 prebendt rails? the rails cost about
$3 at home depot and the meaterials for the whole thing will be about
$100.00 as i plan on doing it all myself, but with the $70 each for the
bendt rails it will be over $400 total, i dont think this job is
worth $300 labor..... any suggestions on bending the rails?????
i tried to bend one by hand to see how far it would bend, it made some
nasty creases as the rails are hollow with a cavity infront of it for
the spline to go into...
any help will be appreciated....
thanks in advance for a answer...

What about installing the spline in the channel, without the screen, to hold the shape while bending?
To do it with a roller you will need a roller formed to the profile
of the lip for the moveabler roller and some way to keep the profile
from swelling when it is bent - basically you need to clamp the frame
to maintain the maximum thickness. Would help too if you were running
annealed material, not material work-hardened by the initial
manufacturing process. If using "mill finish" you could anneal it -
but not using pre-finished.

There's a reason the darn things are $70 a bend. With your $100 bodged
together roller bender your success rate MIGHT be 20% - one in 5
successfull. Doesn't take long to make the ready-bent ones look like a
bargoon.